The present invention relates generally to surgical instruments, and more particularly to a surgical instrument for cutting that has a pair of opposed cutting jaws with concavely curved jaw tips.
There are many different types surgical instruments that include a pair of jaws and that are used to cut bone or other material during surgical procedures. One such instrument is known as a rongeur which has a pair of closeable jaws at one end that are utilized for cutting away bone, and particularly to smooth off a bone surface. A known rongeur instrument has a jaw tip end on each jaw that is outwardly curved or convex in a direction away from the tool or instrument. When a rongeur having a convex jaw tip end is utilized to smooth a bone surface, the device will typically leave small trenches or grooves in the bone surface because of the curvature of the jaw tip ends. This is caused by the convex curve of the jaw tip which leaves a small mirror-image concave groove or trench in the bone during each cut.
For many surgical procedures, this imprecise cutting technique leaves a satisfactory bone surface. However, for certain surgical procedures it is often desirable to leave a smooth bone surface or an outwardly or convex curved bone surface once material has been cut away. For example, when operating on the spine of an individual and approaching the anterior cervical spine, it is beneficial to be able to easily remove bone spurs or anterior osteophytes and also to leave the bone surface relatively smooth and slightly outwardly curved. Following such a procedure, a metal plate is sometimes screwed to the anterior surface of the vertebrae. The smooth and slightly outwardly curved anterior surface allows for better seating of the metal plate and screws. Utilizing a conventional convex curved jaw rongeur essentially prevents one from cutting away these osteophytes and simultaneously leaving the bone or vertebrae with a satisfactorily smooth and curved surface.
In order to overcome the above-described deficiencies in the prior art and other problems, a surgical instrument is provided in accordance with the teachings of the present invention. In one example, a surgical instrument has a pair of opposed jaws that are constructed and arranged to open and close relative to one another. Each jaw has a proximal end connected to part of the surgical instrument, an opposite end or free jaw tip end, and a confronting surface arranged facing the opposite jaw. A perimeter defines a boundary of the confronting surface and jaw tip end of each respective jaw. At least a first cutting edge portion is provided on a part of each jaw perimeter that defines the jaw tip end. Each first cutting edge is oriented such that it extends toward or faces the corresponding first cutting edge portion of the opposite jaw. Each first cutting edge portion is curved concavely inward toward the proximal end of the respective jaw.
In one example, the surgical instrument can be a rongeur surgical instrument for cutting bone.
In one example, a longitudinal axis of the instrument extends in a direction from the proximal end to the free end of the jaws. The curvature or arc of the first cutting edge portion of each jaw tip end is symmetrically arranged relative to the longitudinal axis such that the axis bisects the arc of the first cutting edge portion of each jaw.
In another example, the first cutting edge portion of each jaw tip end is arranged asymmetrically relative to the longitudinal axis. A line that bisects the arc of curvature of each cutting edge portion is disposed at an angle or offset relative to the axis such that the arc is slanted or canted more to one side of the axis.
In one example, each jaw of the surgical instrument can have a pair of spaced apart second cutting edge portions provided on a substantial remaining part of each jaw perimeter. Each pair of second cutting edge portions can continue from opposite ends of the respective first cutting edge portion toward the proximal end of the jaw and can be oriented extending toward the corresponding pair of second cutting edge portions of the opposite jaw. In a further example, a concave hollow can be formed in the confronting surface surrounded by the respective perimeter of each jaw. The hollow can be arranged facing the hollow of the opposite jaw.
In one example, each jaw of the surgical instrument also can have a concave curved end face that is disposed at the jaw tip end and can have a surface curvature that corresponds to a curvature of the concavely curved first cutting edge portion of the respective jaw. In one example, the concavely curved first cutting edge portion of each jaw can have a curvature defined by a two-inch radius arc.
In another example constructed according to the teachings of the present invention, a rongeur surgical instrument has a pair of handles extending from a pivot that are moveable toward and away from one another. The rongeur instrument also includes a pair of opposed jaws that are positioned opposite the handles relative to the pivot and that are constructed and arranged to open and close relative to one another by movement of the handles. In one example, the rongeur surgical instrument is constructed wherein each jaw has a proximal end pivotally coupled to a portion of the instrument, an opposite free jaw tip end, and a confronting surface arranged facing the opposite jaw. Each jaw also has a perimeter that defines a boundary of the confronting surface and jaw tip end of each respective jaw. At least a first cutting edge portion is provided on a part of each jaw perimeter wherein that part of the perimeter defines the jaw tip end. Each first cutting edge portion is oriented extending toward the corresponding first cutting edge portion of the opposite jaw and each first cutting edge portion is curved concavely inward toward the proximal end.
In one example, a longitudinal axis of the instrument extends in a direction from the proximal end to the free end of the jaws. The curvature or arc of the first cutting edge portion of each jaw tip end is symmetrically arranged relative to the longitudinal axis such that the axis bisects the arc of the first cutting edge portion of each jaw.
In another example, the first cutting edge portion of each jaw tip end is arranged asymmetrically relative to the longitudinal axis. A line that bisects the arc of curvature of each cutting edge portion is disposed at an angle or offset relative to the axis such that the arc is slanted or canted more to one side of the axis.
In one example, the rongeur surgical instrument can also have a resilient spring disposed between the handles. The spring can be arranged to bias the handles away from one another and to bias the jaws toward the open position. In another example, the rongeur surgical instrument can be constructed from a stainless steel material.
In another example constructed according to the teachings of the present invention, a rongeur surgical instrument includes a pair of handles extending from a first pivot that are moveable toward and away from one another. Each handle has a drive arm that extends beyond the first pivot opposite the respective handle. A pair of opposed jaws extend from a second pivot and are constructed and arranged to open and close relative to one another. Each jaw has a proximal end with a lever arm extending beyond the second pivot opposite the respective jaw. Each lever arm is pivotally coupled to a corresponding one of the drive arms between the first and second pivots. Each jaw also has an opposite free jaw tip end and a confronting surface arranged facing the opposite jaw. A perimeter defines a boundary of the confronting surface and jaw tip end of each respective jaw. At least a first cutting edge portion is provided on a part of each jaw perimeter wherein that part of the perimeter defines the jaw tip end. Each first cutting edge portion is oriented extending toward the corresponding first cutting edge portion of the opposite jaw and is curved concavely inward toward the proximal end of the respective jaw.
In one example, a longitudinal axis of the instrument extends in a direction from the proximal end to the free end of the jaws. The curvature or arc of the first cutting edge portion of each jaw tip end is symmetrically arranged relative to the longitudinal axis such that the axis bisects the arc of the first cutting edge portion of each jaw.
In another example, the first cutting edge portion of each jaw tip end is arranged asymmetrically relative to the longitudinal axis. A line that bisects the arc of curvature of each cutting edge portion is disposed at an angle or offset relative to the axis such that the arc is slanted or canted more to one side of the axis.
These and other objects, features and advantages of the present invention will become apparent upon a review of the detailed description and accompanying drawing figures set forth herein. There is a need for an improved surgical instrument that overcomes the deficiencies in the prior art described above. The detailed description and drawings herein provide one example of such an improved surgical instrument. Changes and modifications can be made to the disclosed examples and yet fall within the scope of the teachings of the present invention.